Moreover, it wasn't just the preparation for the western campaign but also for the eastern one!
During the months Li Fan had traveled north, the princes and generals of Zhen Country thought that after Triarch's recent defeat, they had lost all face and definitely didn't have the energy to be distracted by other matters before resolving Divine Teachings. Coupled with the initial campaign against Kun Nation, which took three years of arduous preparations, they must unwaveringly overlook the chaotic situation in Zhen state.